I didn't go for the big MXT400 (couldn't justify the price relative to how much I use the thing). But the MXT115 with a big Comet SBB-5 antenna on the front fender is fairly capable. The range on the (ancient tech) CB is respectable too if you can handle running a big antenna (I run a Wilson 2000 on a front fender mount, about 8.5 feet from the ground to the tip of the antenna).
Being that CB is significantly lower frequency than GMRS, there are times it may work better (such as around trees with lots of leaves or in areas with hills). And at this point, there's enough "good" gear out there for not a whole lot of money that it's worth having if you've got the space for it and aren't running 10M HAM gear or something, considering there's no licensing costs to worry about.